焙烧温度对Fe/HZSM-5催化剂催化乙醇制备低碳烯烃性能的影响

摘要

采用浸渍法制备不同温度焙烧的Fe/HZSM-5系列催化剂,并用X射线衍射、NH3-程序升温脱附和H2-程序升温还原等方法对催化剂的物化性能进行表征,在微型固定床反应器上考察焙烧温度对Fe/HZSM-5催化剂催化乙醇制备低碳烯烃性能的影响.结果表明:焙烧温度不同,催化剂的表面酸量、酸强度不同,Fe在催化剂表面的分散度不同;适宜的焙烧温度能够显著提高催化剂的低碳烯烃选择性、抑制芳构化和氢转移反应的发生,当催化剂的焙烧温度为700℃时,反应产物中丙烯和丁烯选择性最高,分别为30.94%和18.01%.%A series of iron-modified HZSM-5 catalysts was prepared by impregnation method and calcined under various temperatures.The obtained samples were characterized using XRD, NH3-TPD and TPR methods.The catalytic properties of the prepared catalysts were investigated by the reactions of converting ethanol into light olefins using a fix-bed micro reactor.It was found that the acidity, acid strength and the dispersion of iron on the catalyst surface changed with the calcination temperature.Fe/HZSM-5 catalyst calcined under optimum temperature could significantly improve the selectivity to light olefins, the hydrogen transfer reactions and aromatization reactions were suppressed.Using catalyst calcined at 700 ℃, the selectivity of propylene and butenes in product was 30.94 ％ and 18.01％, respectively.